A method for determining intra-prediction modes for prediction units (PUs) of a largest coding unit (LCU) is provided that includes determining an inter-prediction mode for each child PU of a PU, and selecting an intra-prediction mode for the PU based on the intra-prediction modes determined for the child PUs.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method comprising: obtaining, by at least one processor, a coding unit (CU) of a video sequence; determining, by the at least one processor, for child prediction units (PUs) of a PU of the CU, a set of low coding cost intra-prediction modes containing a low coding cost intra-prediction mode for each of the child PUs; testing, by the at least one processor, for the PU, only intra-prediction modes from the set of low coding cost intra-prediction modes, to determine a set of coding costs corresponding to the set of low coding cost intra-prediction modes; and selecting, by the at least one processor, a selected intra-prediction mode of the set of low coding cost intra-prediction modes having a low coding cost of the set of coding costs, for the PU.
2. The method of claim 1 , wherein determining the set of low coding cost intra-prediction modes for the child PUs comprises selecting an intra-prediction mode for each child PU of the child PUs from all intra-prediction modes defined for a block size of the child PU.
3. The method of claim 2 , wherein 35 intra-prediction modes are defined for the block size of the child PU.
4. The method of claim 3 , wherein the block size of the child PU is 4×4.
5. The method of claim 1 , wherein the PU consists of four child PUs.
6. The method of claim 1 , further comprising: determining a coding cost of the PU for at least one additional intra-prediction mode; and wherein selecting the selected intra-prediction mode for the PU comprises selecting the selected intra-prediction mode to be an intra-prediction mode having a low coding cost from the set of low coding cost intra-prediction modes and the at least one additional intra-prediction mode.
7. The method of claim 6 , wherein the at least one additional intra-prediction mode consists of two intra-prediction modes surrounding the set of low coding cost intra-prediction modes.
8. The method of claim 1 , further comprising: encoding, by the at least one processor, the video sequence by encoding the PU using the selected intra-prediction mode of the PU, to generate an encoded video sequence; and transmitting, by the at least one processor, the encoded video sequence.
9. A method comprising: obtaining, by at least one processor, a coding unit (CU) of a video sequence; determining, by the at least one processor, an intra-prediction mode for each of N×N prediction units (PUs) of the CU, wherein an intra-prediction mode corresponding to each of the N×N PUs is selected from all intra-prediction modes defined for an N×N PU; and determining, by the at least one processor, an intra-prediction mode for each of 2N×2N PUs of the CU, wherein an intra-prediction mode for each 2N×2N PU is selected from the intra-prediction modes of the N×N PUs contained in a corresponding 2N×2N PU, the determining of the intra-prediction mode for each 2N×2N PUs comprising: determining a coding cost of the 2N×2N PUs for each intra-prediction mode of the N×N PUs in the 2N×2N PUs; and selecting an intra-prediction mode of the N×N PUs having a low coding cost as the intra-prediction mode for the 2N×2N PUs.
10. The method of claim 9 , wherein N=4.
11. The method of claim 9 , wherein 35 intra-prediction modes are defined for an N×N PU.
12. The method of claim 9 , wherein determining the intra-prediction mode for each of the 2N×2N PUs further comprises: selecting the intra-prediction mode of the N×N PUs having a low coding cost as a candidate intra-prediction mode for the 2N×2N PUs; determining a coding cost of the 2N×2N PUs for at least one additional intra-prediction mode; and selecting the intra-prediction mode of the 2N×2N PUs to be an intra-prediction mode having a low coding cost of the candidate intra-prediction mode and the at least one additional intra-prediction mode.
13. The method of claim 9 , further comprising determining an intra-prediction mode for each 4N×4N PU of the CU, wherein an intra-prediction mode for each 4N×4N PU is selected from the intra-prediction modes of the 2N×2N PUs in the 4N×4N PU.
14. The method of claim 9 , further comprising: encoding, by the at least one processor, the video sequence by encoding the CU using the intra-prediction mode of the CU, to generate an encoded video sequence; and transmitting, by the at least one processor, the encoded video sequence.
15. An encoder comprising: at least one processor; and a non-transitory computer readable storage medium storing a program for execution by the at least one processor, the program including instructions to cause the at least one processor to: obtain a coding unit (CU) of a video sequence; determine, for child prediction units (PUs) of a PU of the CU, a set of low coding cost intra-prediction modes, one low coding cost intra-prediction mode for each of the child PUs; test, for the PU, only intra-prediction modes from the set of low coding cost intra-prediction modes for the child PUs, to determine a set of coding costs corresponding to the set of low coding cost intra-prediction modes; and select a selected intra-prediction mode of the set of low coding cost intra-prediction modes having a low coding cost of the set of coding costs, for the PU.
16. The encoder of claim 15 , wherein the instructions to determine the set of low coding cost intra-prediction modes for the child PUs comprise instructions to select an intra-prediction mode for each child PU of the child PUs from all intra-prediction modes defined for a block size of the child PU.
17. The encoder of claim 16 , wherein 35 intra-prediction modes are defined for the block size of the child PU.
18. The encoder of claim 15 , wherein the instructions further comprise instructions to: determine a coding cost of the PU for at least one additional intra-prediction mode; and select the selected intra-prediction mode of the PU to be an intra-prediction mode having a low coding cost from the set of low coding cost intra-prediction modes and the at least one additional intra-prediction mode.
19. The encoder of claim 18 , wherein the at least one additional intra-prediction mode consists of two intra-prediction modes surrounding the set of low coding cost intra-prediction modes.
20. The encoder of claim 15 , wherein the instructions further comprise instructions to: encode the video sequence by encoding the PU using the selected intra-prediction mode of the PU, to generate an encoded video sequence; and transmit the encoded video sequence.
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August 4, 2013
December 8, 2020
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